Image forming apparatus with developing member that supplies toner to surface of image bearing member to form toner image

Abstract

An image forming apparatus comprising: an image bearing member, a developing member that forms a toner image with a toner including a metal soap having a polarity opposite to that of the toner, a supply member that supplies the toner to the developing member, and a control unit that executes a metal soap supply operation of supplying the metal soap from the developing member to the image bearing member when an operation other than the image forming operation is executed, wherein the metal soap supply operation includes a first mode and a second mode, and a potential difference between the supply member and the developing member, which causes an electrostatic force in the direction from the supply member to the developing member to act on the metal soap, is smaller in the metal soap supply operation in the second mode than in the first mode.

What is claimed is: 
     
       1. An image forming apparatus comprising:
 a rotatable image bearing member; 
 a developing member that supplies a toner to a surface of the image bearing member to form a toner image at a developing portion facing the image bearing member; 
 a supply member that supplies the toner to the developing member at a supplying portion in contact with the developing member; and 
 a control unit that executes an image forming operation of forming the toner image on a recording material and a metal soap supply operation of supplying a metal soap that is included in the toner and has a polarity opposite to that of the toner to the surface of the image bearing member when an operation other than the image forming operation is executed, 
 wherein an operation mode of the metal soap supply operation includes a first mode and a second mode, and 
 wherein a potential difference that is formed between the supply member and the developing member and causes an electrostatic force in a direction from the supply member to the developing member to act on the metal soap is smaller at the time of executing the metal soap supply operation in the second mode than at the time of executing the metal soap supply operation in the first mode. 
 
     
     
       2. The image forming apparatus according to  claim 1 , wherein the polarities of the potential difference formed between the supply member and the developing member at the time of executing the metal soap supply operation in the first mode and at the time of executing the metal soap supply operation in the second mode are opposite to each other. 
     
     
       3. The image forming apparatus according to  claim 1 , wherein the polarities of the potential difference formed between the supply member and the developing member at the time of executing the metal soap supply operation in the second mode and at the time of executing the image forming operation are the same. 
     
     
       4. The image forming apparatus according to  claim 1 , wherein a ratio of a surface movement speed of the developing member to a surface movement speed of the image bearing member is larger at the time of executing the metal soap supply operation than at the time of executing the image forming operation. 
     
     
       5. The image forming apparatus according to  claim 1 , wherein a back contrast, which is a difference between a surface potential of the image bearing member in the developing portion and a developing voltage applied to the developing member, is larger at the time of executing the metal soap supply operation than at the time of executing the image forming operation. 
     
     
       6. The image forming apparatus according to  claim 1 , further comprising a transfer member facing the image bearing member with an intermediate transfer member, which is capable of contacting with and separating from the image bearing member, interposed therebetween,
 wherein at the time of executing the metal soap supply operation, the intermediate transfer member is separated from the image bearing member. 
 
     
     
       7. The image forming apparatus according to  claim 1 , further comprising a transfer member facing the image bearing member with an intermediate transfer member, which is capable of contacting with and separating from the image bearing member, interposed therebetween,
 wherein a potential difference that is formed between the image bearing member and the transfer member and causes an electrostatic force in a direction from the image bearing member to the transfer member to act on the metal soap is smaller at the time of executing the metal soap supply operation than at the time of executing the image forming operation. 
 
     
     
       8. The image forming apparatus according to  claim 7 , wherein a voltage applied to the transfer member is 0 V at the time of executing the metal soap supply operation. 
     
     
       9. The image forming apparatus according to  claim 1 , further comprising:
 a charging member that charges the surface of the image bearing member, and 
 an exposure unit that exposes the surface of the image bearing member on an upstream side of a charged portion formed by the charging member, 
 wherein an exposure amount of the exposure unit is smaller at the time of executing the metal soap supply operation than at the time of executing the image forming operation. 
 
     
     
       10. The image forming apparatus according to  claim 9 , wherein the exposure is not performed by the exposure unit at the time of executing the metal soap supply operation. 
     
     
       11. The image forming apparatus according to  claim 1 , further comprising a torque detection unit that detects a drive torque of the image bearing member,
 wherein the control unit executes the metal soap supply operation in a case where the number of rotations of the image bearing member after the last execution of the metal soap supply operation is at least a first threshold value, or in a case where a torque value detected by the torque detection unit is at least a second threshold value. 
 
     
     
       12. The image forming apparatus according to  claim 1 , wherein the control unit executes the metal soap supply operation in the first mode in a case where a total number of rotations of the image bearing member is smaller than a third threshold value, and
 wherein the control unit executes the metal soap supply operation in the second mode in a case where the total number of rotations of the image bearing member is at least the third threshold value. 
 
     
     
       13. The image forming apparatus according to  claim 1 , wherein a ratio of a surface movement speed of the developing member to a surface movement speed of the image bearing member is a value between 85% and 115% at the time of executing the metal soap supply operation. 
     
     
       14. The image forming apparatus according to  claim 1 , wherein at the time of executing the metal soap supply operation, the developing unit comes into contact with the image bearing member at the developing portion. 
     
     
       15. The image forming apparatus according to  claim 1 , wherein a metal type of the metal soap is at least one of zinc, calcium, and magnesium. 
     
     
       16. The image forming apparatus according to  claim 1 , wherein the metal soap is at least one of zinc stearate, calcium stearate, and magnesium stearate. 
     
     
       17. The image forming apparatus according to  claim 1 , wherein the metal soap has a particle diameter of at least 0.15 μm and not more than 2.0 μm. 
     
     
       18. The image forming apparatus according to  claim 1 , wherein the image bearing member has a protective layer configured of an acrylic resin on an outermost surface layer. 
     
     
       19. An image forming apparatus comprising:
 a rotatable image bearing member; 
 a developing member that supplies a toner to a surface of the image bearing member to form a toner image at a developing portion facing the image bearing member; 
 a supply member that supplies the toner to the developing member; and 
 a control unit that executes an image forming operation of forming the toner image on a recording material and a metal soap supply operation of coating a metal soap that is included in the toner and has a polarity opposite to that of the toner on the surface of the image bearing member by supplying the toner from the developing member to the surface of the image bearing member when an operation other than the image forming operation is executed, wherein the operation mode of the metal soap supply operation includes a first mode and a second mode, 
 wherein an amount of the metal soap supplied from the developing member to the surface of the image bearing member is smaller at the time of executing the metal soap supply operation in the second mode than at the time of executing the metal soap supply operation in the first mode, and 
 wherein the polarities of the potential difference formed between the supply member and the developing member at the time of executing the metal soap supply operation in the first mode and at the time of executing the metal soap supply operation in the second mode are opposite to each other. 
 
     
     
       20. The image forming apparatus according to  claim 19 , wherein a potential difference that is formed between the supply member and the developing member and causes an electrostatic force in a direction from the supply member to the developing member to act on the metal soap is smaller at the time of executing the metal soap supply operation in the second mode than at the time of executing the metal soap supply operation in the first mode. 
     
     
       21. The image forming apparatus according to  claim 19 , wherein a ratio of a surface movement speed of the developing member to a surface movement speed of the image bearing member is smaller at the time of executing the metal soap supply operation in the second mode than at the time of executing the metal soap supply operation in the first mode. 
     
     
       22. The image forming apparatus according to  claim 19 , wherein a back contrast, which is a difference between a surface potential of the image bearing member in the developing portion and a developing voltage applied to the developing member, is smaller at the time of executing the metal soap supply operation in the second mode than at the time of executing the metal soap supply operation in the first mode. 
     
     
       23. The image forming apparatus according to  claim 19 , further comprising a transfer member facing the image bearing member with an intermediate transfer member, which is capable of contacting with and separating from the image bearing member, interposed therebetween,
 wherein the intermediate transfer member is in contact with the image bearing member at the time of executing the metal soap supply operation in the first mode, and the intermediate transfer member is separated from the image bearing member at the time of executing the metal soap supply operation in the second mode. 
 
     
     
       24. The image forming apparatus according to  claim 19 , further comprising a transfer member facing the image bearing member with an intermediate transfer member, which is capable of contacting with and separating from the image bearing member, interposed therebetween,
 wherein a potential difference that is formed between the image bearing member and the transfer member and causes an electrostatic force in a direction from the image bearing member to the transfer member to act on the metal soap is larger at the time of executing the metal soap supply operation in the second mode than at the time of executing the metal soap supply operation in the first mode. 
 
     
     
       25. The image forming apparatus according to  claim 19 , further comprising:
 a charging member that charges the surface of the image bearing member, and 
 an exposure unit that exposes the surface of the image bearing member on an upstream side of a charged portion formed by the charging member, 
 wherein an exposure amount of the exposure unit is larger at the time of executing the metal soap supply operation in the second mode than at the time of executing the metal soap supply operation in the first mode. 
 
     
     
       26. The image forming apparatus according to  claim 25 , wherein the exposure is not performed by the exposure unit at the time of executing the metal soap supply operation in the first mode. 
     
     
       27. An image forming apparatus comprising:
 a rotatable image bearing member; 
 a developing member that supplies a toner to a surface of the image bearing member to form a toner image at a developing portion facing the image bearing member; and 
 a control unit that executes an initial operation of causing the image bearing member to make a transition from a new state to a print-ready state and an image forming operation of forming the toner image on a recording material, 
 wherein a first peripheral speed ratio, which is the ratio of a surface movement speed of the developing member to a surface movement speed of the image bearing member in at least a part of a period of time in which the initial operation is executed, is larger than a second peripheral speed ratio, which is a ratio of the surface movement speed of the developing member to the surface movement speed of the image bearing member at the time of executing the image forming operation, 
 wherein the first peripheral speed ratio is larger than 100%, and 
 wherein the second peripheral speed ratio is not larger than 100%. 
 
     
     
       28. The image forming apparatus according to  claim 27 , wherein at the time of executing the initial operation, a potential difference causing an electrostatic force in a direction from a supply member, which supplies the toner to the developing member, toward the developing member to act on the toner is formed between the supply member and the developing member. 
     
     
       29. The image forming apparatus according to  claim 27 , further comprising a transfer member facing the image bearing member with an intermediate transfer member, which is capable of contacting with and separating from the image bearing member, interposed therebetween,
 wherein at the time of executing the initial operation, the intermediate transfer member is separated from the image bearing member. 
 
     
     
       30. The image forming apparatus according to  claim 27 , further comprising:
 a charging member that charges the surface of the image bearing member, and 
 an exposure unit that exposes the surface of the image bearing member on an upstream side of a charged portion formed by the charging member, 
 wherein an exposure amount of the exposure unit is smaller at the time of executing the initial operation than at the time of executing the image forming operation. 
 
     
     
       31. The image forming apparatus according to  claim 30 , wherein the exposure is not performed by the exposure unit at the time of executing the initial operation. 
     
     
       32. The image forming apparatus according to  claim 27 , further comprising a torque detection unit that detects a drive torque of the image bearing member,
 wherein the control unit makes the first peripheral speed ratio larger than the second peripheral speed ratio in a case where a torque value detected by the torque detection unit at the time of executing the initial operation is at least a fourth threshold value. 
 
     
     
       33. The image forming apparatus according to  claim 27 , wherein the toner includes a metal soap having a polarity opposite to that of the toner. 
     
     
       34. The image forming apparatus according to  claim 33 , wherein the control unit executes an initial supply operation of supplying the metal soap contained in the toner from the developing member to the image bearing member in at least a part of a period of time in which the initial operation is executed. 
     
     
       35. The image forming apparatus according to  claim 34 , further comprising a supply member that supplies the toner to the developing member,
 wherein a potential difference that is formed between the supply member and the developing member and causes an electrostatic force in a direction from the supply member to the developing member to act on the metal soap is larger at the time of executing the initial supply operation than at the time of executing the image forming operation. 
 
     
     
       36. The image forming apparatus according to  claim 33 , further comprising a transfer member facing the image bearing member with an intermediate transfer member, which is capable of contacting with and separating from the image bearing member, interposed therebetween,
 wherein a potential difference that is formed between the image bearing member and the transfer member and causes an electrostatic force in a direction from the image bearing member to the transfer member to act on the metal soap is smaller at the time of executing the initial operation than at the time of executing the image forming operation. 
 
     
     
       37. The image forming apparatus according to  claim 36 , wherein at the time of executing the initial operation, a voltage applied to the transfer member is 0 V. 
     
     
       38. The image forming apparatus according to  claim 27 , wherein at the time of executing the initial operation, the developing member comes into contact with the image bearing member at the developing portion.